For autonomous driving systems and driver-assistance systems to safely pilot vehicles, the systems may need to be able to determine the current state of road conditions with a high degree of accuracy, including conditions that were initially intended for use by a human. For example, throughout the world, traffic lights are used to determine whether a vehicle is permitted to proceed into an intersection or is required to stop before entering the intersection. An autonomous driving system or driver-assistance system controlling the vehicle may need to successfully identify such traffic lights and determine the state of a traffic light in order to safely control the vehicle in the vicinity of the intersection. While recognizing a traffic light and determining the state of a traffic light with a high degree of accuracy is needed, power consumption by an autonomous driving system is also a concern, especially when such a system is installed on an electric vehicle.